The disclosure relates to an electrophoresis device in which a plurality of electrophoretic particles are contained in an insulating liquid, and to a display unit including the electrophoresis device.
In recent years, low-power display units (displays) with high image quality have been in increasing demand, as mobile equipment represented by portable telephones and portable information terminals has become widespread. Above all, portable information terminals provided for the purpose of reading character information for a long time (namely, electronic book terminals) have been attracting attention recently since the appearance of distribution service of electronic books. Therefore, displays having display quality suitable for this purpose have been desired.
Displays such as a cholesteric liquid crystal display, an electrophoretic display, an electric-redox-type display, and a twisting ball display have been proposed as displays for reading purpose. Above all, a reflection-type display is desirable. This is because, in this type of display, bright display is performed using reflection (scattering) of external light in a manner similar to paper and thus, display quality close to that of paper is achieved. In addition, since backlight is unnecessary, power consumption is low.
A strong candidate of the reflection-type display is an electrophoretic display that produces contrast using an electrophoretic phenomenon. The reason is that the electrophoretic display is superior in rapid response while consuming low power. Thus, various studies have been made for a display method of the electrophoretic display.
Specifically, there has been proposed a method in which two kinds of charged particles which are different in optical reflection property are dispersed in an insulating liquid, and the charged particles are moved in response to an electric field (for example, see Japanese Examined Patent Publication No. S50-015115 and Japanese Patent No. 4188091). In this type of method, the two kinds of charged particles are of opposite polarity and therefore, distribution of the charged particles changes in response to an electric field.
In addition, there has been proposed a method in which a porous layer is arranged and charged particles are dispersed in an insulating liquid, and the charged particles are moved through pores of the porous layer in response to an electric field (for example, see Japanese Unexamined Patent Application Publication Nos. 2005-107146, 2005-128143, and 2002-244163, and also Japanese Examined Patent Publication No. S50-015120. In this type of method, a polymeric film in which pores are formed by perforation processing using a laser, a cloth woven of synthetic fiber, a continuous-bubble porous polymer, or the like is used for the porous layer.